DNA ENCODING TWO FISH NEUROPEPTIDES

Abstract: Novel DNAs are provided which code for fish PACAP and GHRH-like peptide. Methods are provided for production of fish PACAP and fish GHRH-like peptide by expression of the novel DNAs. Additionally, methods are provided for producing enhanced growth of fish by transfection with the novel DNAs of the invention. Further a method is provided for identification of transgenic fish.

Description: DNA ENCODING TWO FISH NEUROPEPTIDES The present invention relates to fish neuropeptides. More particularly, it relates to novel cDNA sequences coding for precursors of two fish neuropeptides, pituitary adenylate cyclase activating polypeptide (PACAP) and growth hormone-releasing hormone-like peptide (GHRH-like peptide) , and to novel precursor proteins for these two peptides. It relates also to methods for producing enhanced growth of fish. BACKGROUND OF THE INVENTION The glucagon superfamily contains a number of members including glucagon, vasoactive intestinal polypeptide (VIP) , peptide histidine methionine (PHM) , peptide histidine isoleucine (PHI) , secretin, gastric inhibitory peptide, growth hormone-releasing hormone (GHRH) , helospectin and helodermin. Recently, two new candidates, pituitary adenylate cyclase activating peptide (PACAP) and PACAP-related peptide (PRP) were added for mammals. Structurally, they resemble VIP and GHRH, respectively. cDNAs coding for PACAP have been obtained from sheep, rats and humans [Ogi et al., (9), Kimura et al., (8)]. In mammals, these cDNAs also code for a second peptide called PACAP-related peptide or PRP [Ogi et al. , (9), Kimura et al., (8)]. No biological function has so far been reported for PRP and it has not yet been isolated from mammalian tissues. Another member of the glucagon superfamily, GHRH, is encoded in mammals in a separate gene in a separate chromosome from the gene for PACAP and PRP (Mayo et al. , 66) . Mammalian GHRH stimulates the synthesis of growth hormone (GH) in the anterior pituitary, stimulates release of GH from anterior pituitary cells both in vivo and in vitro. stimulates an increase in proliferation of GH-producing cells, stimulates an increase in GH mRNA in pituitary cells in vitro and induces transcription of the GH gene in cell culture and in vivo. Mammalian GHRH does not stimulate release of other pituitary hormones (62, 38, 33, 64, 65, 67, 68 and 63). Much less is known about PACAP and GHRH in fish. Vaughan et al., (11), have isolated a GH-releasing factor from carp hypothalamic tissue and determined its amino acid sequence. Fish PACAP has not been reported prior to the work of the present inventors. It was therefore not previously known whether fish PACAP, if it existed, is encoded on a gene which also encodes an additional peptide, as for mammalian PACAP. The present inventors have now shown that there is a PACAP in fish and that this peptide is encoded along with an additional peptide on one gene. Surprisingly, they have shown that in fish, this second peptide is a GHRH-like peptide. This second peptide appears to be equivalent to mammalian GHRH which is encoded on a quite separate chromosome from PACAP in mammals. SUMMARY OF INVENTION In accordance with one aspect of the invention, novel DNA molecules are provided comprising nucleotide sequences encoding fish GHRH-like peptide and fish PACAP or encoding both peptides. In accordance with a further aspect of the invention, fish PACAP and GHRH-like peptide precursor proteins are provided. In accordance with a further aspect of the invention, substantially pure fish PACAP and substantially pure fish GHRH-like peptide are provided. In accordance with a further aspect of the invention, a method is provided for producing fish PACAP and fish GHRH-like peptide, as well as novel hosts transformed with DNA molecules encoding these peptides. In accordance with a further aspect of the invention, novel DNA constructs are provided comprising the novel DNA molecules of the invention operatively associated with a suitable promoter and transcription termination sequence. In accordance with a further aspect of the invention, a method is provided for producing enhanced growth of a fish comprising introducing into fertilised eggs of the fish novel DNA constructs of the invention whereby expression of the DNA construct during growth of the eggs into fish produces PACAP and GHRH-like peptide and gives enhanced growth of the fish. In accordance with a further aspect of the invention a method is provided for identifying a transgenic fish containing a DNA construct comprising a transfeeted DNA flanked by at least one heterologous DNA sequence comprising the steps of obtaining a sample of DNA from said fish; amplifying the DNA of the sample by PCR using at least one primer DNA sequence hybridisable to a portion of the DNA construct in the region of the junction between the transfected DNA and the at least one heterologous DNA sequence; and detecting said amplified DNA which is indicative of a transgenic fish. DESCRIPTION OF DRAWINGS Certain embodiments of the invention are described, reference being made to the accompanying drawings wherein: Figure 1 shows the nucleotide sequence and deduced amino acid sequence of sockeye salmon GHRH/PACAP cDNA. The putative signal peptide and polyadenylation signal (ATTAAA) are underlined. The GHRH-like peptide, amino acids 82-126, and PACAP38, amino acids 129-166, are boxed. Nucleotide substitutions and resulting amino acid changes noted in additional clones are shown below the main reading frame. Figures 2a and 2b show the nucleotide sequence and deduced amino acid sequence of Thai catfish GHRH/PACAP cDNA. Figure 3 shows the nucleotide sequence and deduced amino acid sequence (Sequence ID No: 1) of a portion of sturgeon GHRH/PACAP cDNA. Figure 4 is a schematic diagram of the strategy used for PCR and RACE to amplify salmon cDNA. 4A shows amplification of double stranded cDNA using primer CSC33 (5 , CA(T/C)GCIGA(T/C)GGIATGTT(T/C)AA3 / : Sequence ID No: 12) and primer oligo (dT) (GAATTCT(dT)36) [UT = untranslated] ; 4B shows reverse transcription using sequence specific primer NMS3 (5'TCGGTAGCGGCTG TAGCTATCTG3':Sequence ID No: 15) to obtain 5' region; 4C shows tailing of single stranded cDNA with dATP and subseejuent amplification using internal primer NMS1 (5'TGACAGAGGCTCTGTGTC3':Sequence ID No: 14) and primers #2 (GGCTCGAGCCCGGGAATTCCG(dT)15:Sequence ID No:18) and #3 (5'GGCTCGAGGCCCGGGAATTCCG3' :Sequence ID No: 19) [SP = signal peptide]. Figure 5 shows a restriction map of sockeye salmon GHRH/PACAP cDNA indicating the unigue restriction sites. Figures 6a and 6b show a comparison of salmon GHRH/PACAP precursor with the three mammalian PACAP precursors. Amino acids different from the salmon precursor are shown, while identical residues are not. The signal peptide of the salmon precursor is underlined and the peptide regions of all the precursors are boxed. Figure 7 shows a comparison of the deduced amino acid sequence of salmon GHRH-like peptide with the deduced amino acid sequences of catfish and sturgeon GHRH-like peptides and with the deduced sequence of mouse GHRH and the reported sequences of carp, rat, sheep, goat, cow, pig and human GHRHs. Amino acids different from the salmon molecule are shown as letters and SUBSTITUTESHEET identical residues are shown by the dots ( * ) . Bars (-) represent spaces where the sequence was shifted to obtain maximum alignment of the peptides. Percent sequence identity to the salmon hormone is shown on the right. Figure 8 shows a comparison of all the GHRH/PACAP precursor clones that contained a 5' untranslated region. Identical nucleotides among the different clones are in bold and underlined (single) . Additional start codons (ATG) are double underlined. Nucleotides are numbered negatively from the start codon (not shown) on right. Figure 9 shows a comparison of the 3' untranslated region of the salmon preproGHRH/PACAP with the beginning of the 3' untranslated regions of human, ovine and rat preproPACAPs. Nucleotides identical to the salmon for any of the three mammalian forms are shown by an *. Where a nucleotide is not identical to the salmon, but at least one of the mammalian forms is, this nucleotide is in bold. Gaps (-) were inserted for maximum sequence alignment. The salmon polyadenylation (ATTAAA) is underlined. Nucleotide changes in clone SS/PCR 5 are shown above the salmon clone SS/PCR 4 sequence. Figure 10 shows the nucleotide sequences and deduced amino acid sequence of chum salmon short precursor cDNA, from clones CS/LIBa (A) and CS/LIBb (B) . Nucleotides in the 5' untranslated region which are different in the two clones are shown in bold. A putative ATG start codon in the 5' untranslated region of clone CS/LIBb is shown by the double underline. A Cys in position 22, represented by *** / is identical to the full length clone SS/PCR 7, but different from that of SS/PCR 2. Putative signal peptide is underlined. Figure 11a shows the GH releasing activity of salmon GHRH-like peptide and Figure lib that of salmon PACAP. Figure 12 shows the GH releasing activity of salmon GHRH-like peptide compared with human GHRH^g after 1 hour, 2 hours or 4 hours of incubation with salmon pituitary cells. SST = somatostatin. SUBSTITUTESHEET Figure 13a shows salmon GHRH-like peptide and Figure 13b salmon PACAP-38, compared to the other members of the glucagon superfa ily. Amino acids identical to the salmon sequences are shown by the dots (') . Percent sequence identity to the salmon sequences is shown on the right. GHRH = growth hormone releasing hormone; PHM-27 = peptide histidine-methionine; PHI-27 = peptide histidine- isoleucine; VIP - vasoactive intestinal peptide; GLP = glucagon-like peptide; GIP = gastric inhibitory peptide; PACAP = pituitary adenylate cyclase activating polypeptide. Figure 14 shows a comparison of salmon GHRH-like peptide with mammalian PRP's (48 amino acids). Figures 15a and 15b show a comparison of catfish and salmon cDNA and derived amino acid sequences. Figure 16 shows a schematic diagram comparing the precursor for salmon, catfish and sturgeon GHRH/PACAP, deduced from cDNA sequences (a.a = amino acids). DETAILED DESCRIPTION OF THE INVENTION In the description which follows, references are made to certain literature citations which are listed at the end of the specification. The following abbreviations are used in the specification: CS chum salmon LIB. library PCR polymerase chain reaction RACE rapid amplification of cDNA ends SS sockeye salmon The inventors have isolated and characterised novel fish cDNA sequences which code for unique precursor proteins which contain two biologically active hormones. The hormones encoded in these novel cDNA sequences are a GHRH-like peptide and PACAP. SUBSTITUTESHEET Similar organization of the fish cDNA has been found in all three species examined, salmon, catfish and sturgeon. This is in complete contrast to the mammalian genome, where PACAP is encoded on a gene also coding for PRP, while the GHRH gene occurs on a separate chromosome. Isolation and identification of salmon GHRH/PACAP DNA and precursor ssqusness using PCR and RACE A novel cDNA was isolated from sockeye salmon brain by using PCR with a combination of novel primers. mRNA was isolated from brain tissue and cDNA was prepared as described in Example 1.1. The cDNA was amplified as described in Example 1.2 and 1.3, the strategy being set out in Figure 4. The DNA was cloned and sequenced as described in Example 1.4 and 1.5. A degenerate primer CSC33 based on conserved sequences of GHRH peptides in human, rat and carp was used with an oligo dT primer in the PCR to amplify a 425 bp cDNA fragment (Fig. 4A) . This cDNA was subsequently cloned into pBluescript KS II. Two clones designated SS/PCR 4 and SS/PCR 5 were sequenced and each was found to contain a GHRH-like and PACAP sequence (bp position 244-668, Fig. 1). These two clones differed at 12 bp positions and clone SS/PCR 5 had a deletion of 4 bases (Fig. 1) . Three amino acid substitutions between the clones resulted from the nucleotide changes (Fig. 1) . To identify the cDNA sequence 5' to the coding region of the GHRH-like region, the RACE reaction was used (Fig. 4B and 4C) . A cDNA fragment of approximately 417-462 bp was cloned and sequenced (bp positions -84 to 378 (Fig. 1) . Two of 32 plasmid preparations contained the 5' GHRH-like region as identified with PCR. These two clones, SS/RACE 2 and SS/RACE 7, were different at 3 nucleotide positions within the translated region resulting in 3 amino acid changes (Fig. 1) . The 5' untranslated regions are discussed below. A full length GHRH/PACAP cDNA was obtained by digesting the two overlapping clones, SS/RACE 2 and SS/PCR 4, with Nco I (Fig. 5) and Not I. The cleavage site for the restriction enzyme Not I is located in the multiple cloning region of pBluescript II KS. After removal of the fragment from clone SS/PCR 4, the fragment obtained from clone SS/RACE 2 was ligated into clone SS/PCR 4. This resulted in a PACAP cDNA clone of 707 bp with an open reading frame of 173 amino acids. This cDNA was sequenced as described in Example 1.5 and the nucleotide sequence is shown in Figure l. Organisation of the salmon GHRH/PACAP precursor The deduced amino acid sequence corresponding to salmon GHRH/PACAP cDNA is also shown in Figure 1. The salmon GHRH/PACAP precursor protein has 173 amino acids comprising four distinct domains: a signal peptide (22 residues) , a cryptic peptide which follows the signal peptide (59 residues) , the GHRH-like region (45 residues) and PACAP (38 residues) . The signal peptide of the salmon GHRH/PACAP precursor has a hydrophobic core and is two amino acids shorter than the signal peptide of the ovine [8], human [1,8] and rat [9] PACAP precursors (Fig. 6) . At the amino acid level, there is 77% sequence identity between the salmon signal peptide and human PACAP signal peptide. A cysteine at position 22 of the signal peptide in some of the salmon GHRH/PACAP clones is identical to that of the rat, while the serine in clone SS/PCR 4 is the same as the human cDNA (Fig. 4) . The presence of two dibasic enzyme processing sites and a single arginine enzyme processing site would be expected to result in the cleavage of the precursor into a GHRH-like peptide of 45 amino acids with a free hydroxyl carboxy terminus and a PACAP of 38 amino acids with an amidated carboxy terminus. The single Arg processing site precedes the GHRH-like molecule and the dibasic Lys-Arg processing site follows (Figs. 1 and 6) . The salmon PACAP is preceded by a Lys-Arg enzyme processing site and has a Gly-Arg-Arg at its carboxy terminus. In addition, within the GHRH-like peptide, there is a Lys-Arg site; cleavage at this site will result in a 28 residue peptide, GHRH-like peptide 28. Within the PACAP-38 peptide, there is a Gly-Lys-Arg site; processing at this site will give a 27 residue peptide, PACAP-27. Isolation and identification of catfish GHRH/PACAP DMA and precursor sequences using a catfish probe to screen a cDMλ catfish brain library • A novel cDNA was isolated from catfish by screening a catfish brain cDNA library with a catfish GHRH/PACAP probe synthesized by PCR. mRNA was isolated from brain tissue and cDNA was prepared as described in Example 4.1. A cDNA library was prepared from catfish brains; a lysate was then prepared from the library as described in Example 4.2. Nondegenerate primers [SP1, NMS3, NMS4] based on the salmon GHRH/PACAP cDNA sequence were used with the catfish lysate DNA in a polymerase chain reaction (PCR) to amplify a 393 bp cDNA fragment as described in Example 4.3. This cDNA was subsequently cloned into pBluescript KS II as described in Example 4.4. The cloned cDNA was sequenced as described in Example 4.5 and found to contain a sequence that included the coding for a complete GHRH-like peptide and a partial PACAP sequence (bp positions 43 to 429, Fig. 2) . To isolate a full length cDNA clone, the 393 bp PCR fragment was used as a probe to screen the catfish cDNA library as described in Example 4.6. One positive clone was isolated and sequenced as described in Example 4.7. The sequence of this full length clone of approximately 2500 bp is shown in Fig. 2. A Northern blot was done with the 393 bp probe as described in Example 4.8 to confirm that one band on the blot was similar in size with the cDNA shown in Fig. 1. SP1: 5'GGAATCATAATGCACTACAGTGTC3' (Sequence ID No: 13) NMS4: 5'CTACACGCTTTGCCATCAGAGA3• (Seejuence ID No: 16) Isolation and identification of sturgeon GHRH DMA and precursor sequences using PCR A novel cDNA was isolated from sturgeon brain by using PCR with a combination of primers made to the salmon cDNA. mRNA was isolated from brain tissue and cDNA was prepared as described in Example 5.1. , The cDNA was amplified, cloned and sequenced as described in Example 5.2. Nondegenerate primers [SP1 and NMS3] based on the salmon GHRH/PACAP sequence were used with sturgeon single stranded cDNA in a polymerase chain reaction to amplify a 339 bp cDNA fragment as described in Example 5.2. This cDNA was subsequently cloned into pBluescript KS II and sequenced as described in Example 5.2. The cDNA fragment was found to contain a sequence that included the coding for a complete GHRH-like peptide and a partial PACAP sequence (bp positions l to 339, Fig. 3). The nucleotide sequences of catfish and sturgeon cDNA are shown in Figures 2 and 3 respectively, as well as the corresponding amino acid sequences. The catfish GHRH/PACAP precursor protein has 180 amino acids and comprises the same four domains as the salmon protein. The catfish and salmon precursors contain signal and cryptic peptides that are similar in length, but have only 68% (signal peptide) or 48% (cryptic peptide) sequence identity. The catfish and salmon GHRH-like peptides are both 45 amino acids, although the catfish GHRH may have an extended amino terminus of 3 amino acids, depending on the cleavage site. If the arg-arg site (amino acid positions 78-79, Fig. 2) is cleaved, catfish GHRH would be expected to be 48 amino acids, but if the Thr site (amino acid position 82) is cleaved, catfish GHRH would be expected to be 45 amino acids. The catfish and salmon GHRH have 62% sequence identity. Both catfish and salmon precursors have a dibasic enzyme processing site between GHRH and PACAP. The catfish and salmon PACAP precursors have cleavage sites that would be expected to produce PACAP27 and/or PACAP38 (salmon) or PACAP 39 (catfish) . Catfish PACAP27 has 78% and PACAP39 has 61% sequence identity to salmon PACAPs. PACAP39 in catfish is not expected to be amidated. Both catfish GHRH45 and PACAP have histidine at the amino terminus. The PCR product prepared from sturgeon brain cDNA contained a region from the end of the signal peptide to amino acid 6 of PACAP. The complete GHRH sequence derived from this PCR product showed a 45 amino acid peptide with a free hydroxyl carboxy terminus. Sturgeon GHRH-like peptide has higher (84%) sequence identity to salmon GHRH than does catfish GHRH. A dibasic enzyme processing site separates the GHRH-like peptide from the amino terminus of PACAP as described for the salmon and catfish precursors. The amino acid sequence identity of the various peptides of salmon, catfish and partial sturgeon precursors are shown in Table I in relation to each other and in Table II in relation to human PACAP precursor. Figure 16 shows the peptide positions in the three precursors. In accordance with one embodiment of the present invention, novel cDNAs are provided which are useful for the production of fish GHRH-like peptide and fish PACAP. Chemical synthesis of a peptide of 38 or 45 amino acids in length is cumbersome and expensive. The novel cDNAs of the invention may be expressed in known expression systems thus providing a convenient and more efficient method for producing quantities of fish PACAP and/or fish GHRH-like peptide. These peptides are useful either singly or in combination to enhance growth of fish by stimulation of endogenous growth hormone secretion. The peptides may be administered to fish by injection, intraperitoneally or intramuscularly. For optimal growth enhancement, however, it is preferable that the peptides are administered to the fish continuously over a period of time. This may be done by administering the peptides in a slow release type of composition, such as implanted cholesterol pellets incorporating either or both peptides. Alternatively, either or both peptides may be incorporated into fish food and administered orally. In accordance with a preferred embodiment, a cDNA encoding both GHRH-like peptide and PACAP is expressed to produce both peptides. To produce salmon GHRH-like peptide and PACAP, a DNA comprising nucleotides -39 to 668 of Figure 1 is expressed, or a degeneracy equivalent or an effective portion or analog thereof. To produce catfish GHRH-like peptide and PACAP, a DNA comprising nucleotides - 321 to 2181 of Figure 2 is expressed, or a degeneracy equivalent or an effective portion or analog thereof. Optionally, a single peptide may be produced by expression of a suitable cDNA. For salmon PACAP, a cDNA comprising nucleotides -51 to 357 of nucleotide sequence A of Figure 10 may be employed. A short cDNA containing GHRH, but not PACAP, is produced using PCR and specific primers. For example, primer 1 is made to the 5' untranslated region or any region 5' to the GHRH coding region and primer 2 is made to the 3' end of the GHRH coding region. A short cDNA containing PACAP, but not GHRH, of a type similar to that in Figure 10, could be expressed for production of PACAP only. The novel cDNAs of the invention may be expressed by methods known to those skilled in the art. The selected cDNA is ligated into a suitable expression vector downstream from a suitable promoter as described in Sambrook et al., (79) and in (32). A translation initiating codon, ATG, and translation termination codons (TAA, TGA, or TAG) may be added if required. Suitable expression vectors include bacteriophage such as λgtll or λZap II, plasmids such as pUC 12 and pUC 13, and animal viruses such as retroviruses and vaccinia viruses. Any promoter may be used,which is suitable for expression in the selected host cell. Suitable host cells include animal cells such as Chinese hamster cell (CHO) , rat GH4 pituitary cell, and adrenal medullary cell (PC12) , bacterial cells or yeasts. A preferred promoter is that obtained from the fish growth hormone gene. The transformation of bacteria, yeast and animal cells is as described in [32] and Sambrook. The transformants are cultivated in the appropriate media. The expressed GHRH/PACAP precursor protein or mature peptide can be extracted from the culture as described by Parker and Sherwood (80) . Active fractions from HPLC are detected by immunoassay using antisera to salmon GHRH or salmon PACAP. In addition, other known methods could be used for the GHRH and/or PACAP peptide purification. Expression in neuroendocrine cells such as pituitary GH4 and adrenal medulla PC12 cells will give secretion of mature peptides [Steiner et al., (81)]. Further, both peptides will be secreted from the full length cDNA whereas the single peptides will be produced from the shortened cDNA. If expression is carried out in bacteria, precursor proteins will be secreted. The cells transfected or transformed with the DNA of the present invention can produce a large amount of the precursor protein or the mature peptides. In accordance with a further embodiment of the invention, novel DNA constructs may be prepared containing the novel cDNAs of the invention; such constructs are useful to produce transgenic fish with increased production of GHRH-like peptide and/or PACAP resulting in increased growth. Increased growth of transgenic fish transfected with a gene for fish GH has been demonstrated by Du et al. (69) and Zhu (70) . It has also been shown that mice transgenic for human GHRH had elevated levels of endogenous GH and showed enhanced growth [Hammer et al., (71)]. In contrast to GH-transgenic mice, all of the hGHRH- transgenic mice were fertile, suggesting that GHRH produces a more physiological effect on growth and reproduction. In accordance with a further embodiment of the invention, a novel method is provided for producing enhanced growth of fish comprising transfecting the fish by introduction into fish eggs of a novel DNA of the invention, to produce expression of the DNA and production of GHRH-like peptide and/or PACAP whereby growth of the fish is enhanced. This method of producing enhanced fish growth offers some advantages over direct administration of GHRH-like peptide and/or PACAP to fish. As indicated above, for optimal growth enhancement, exposure to the peptides may have to be continued over considerable periods of time, depending on the fish species. Repeated handling of fish for sequential treatments with peptides is, however, liable to cause stress syndrome; this risk can be avoided by the transfection method. For transfection of fish with the novel DNAs of the invention, a selected DNA encoding the peptide or peptides to be expressed in the fish is operatively linked to a suitable upstream promoter and a suitable downstream transcription termination sequence ligated into a plasmid to form a DNA construct. The promoter and transcription termination sequence are ligated to the selected DNA by conventional methods, as will be understood by those skilled in the art. Suitable promoters include RSV and TK. A promoter obtained from fish is preferred. Suitable fish promoters include GH, PRL & GTH. The transcription termination sequence of the construct may be that associated with the selected DNA or may be another suitable transcription termination sequence. A fish transcription termination sequence is preferred. . In accordance with an especially preferred embodiment of the invention, a DNA construct comprises a selected DNA in accordance with the invention encoding the peptide or peptides to be expressed in the fish, operatively linked to a fish growth hormone gene promoter and a fish growth hormone gene transcription termination sequence in a suitable plasmid such as pUC 18 or pUC19. Such growth hormone promoters and transcription termination sequences are described in Du et al. (70) . This construct, having growth hormone gene promoter and transcription termination sequence, will be expressed in the pituitary which contains the endoproteases required for proper cleavage of the precursor proteins and where expression of the DNA will escape the control system operating on GHRH-like peptide expression and PACAP expression in brain tissue and which contains target receptors. Suitable methods for introducing the construct into fish to produce transgenic fish are described by Hew et al. (75). A preferred method is microinjection of the construct containing the selected DNA in accordance with the invention into fertilised, but not activated, teleost eggs. Fertilised teleost eggs can be injected relatively easily through the micropyle using a very fine glass needle (2-3μm) [Fletcher et al. (76)]. Microinjection through the micropyle facilitates the procedure by 1) allowing for easier access to the egg cytoplasm and 2) providing a means of locating and introducing the vector in close proximity to the yet uncombined male and female pronuclei thereby increasing the chances of single cell genomic integration. Other methods of preparation of transgenic fish include introducing the vector by electroporation [Neuman et al., (77)] CaCl 2 precipitation, or lipofection [Feigner et al., (78)]. In accordance with a further embodiment of the invention, a method is provided for identifying a transgenic fish carrying a novel DNA construct in accordance with the invention. As described above, a DNA construct is created comprising a novel DNA coding for fish GHRH-like peptide and PACAP, or a shorter DNA coding for one of these peptides, ligated between a promoter and a transcription termination sequence (TTS) . When the promoter and TTS are obtained from a gene other than the PACAP/GHRH gene, fish transfected with such a DNA construct carry unique DNA sequences which may be used to identify the transgenic fish, as will be described. The genome of a non-transgenic fish lacks any portion comprising GHRH/PACAP DNA, GHRH DNA or PACAP DNA joined to a heterologous promoter and/or a heterologous TTC. If PCR amplification of a sample of fish DNA is carried out using a first primer which hybridises to a stretch of DNA spanning the junction between the heterologous promoter and the GHRH/PACAP DNA, or to a stretch of DNA spanning the junction between the GHRH/PACAP DNA and the heterologous TTS, and a second primer which hybridises to a portion of the GHRH/PACAP DNA insert, an amplified DNA is produced only from the DNA of transgenic fish. As will be understood by those skilled in the art, a variety of primers may be made by conventional methods and used in this method for identification of transgenic fish, provided that one primer is generated to a unique site at the junction between the DNA insert and the heterologous flanking regions. For analysis, DNA may be obtained from a variety of fish tissues, including blood and fin tissue. Where a DNA construct is created using a promoter and TTS obtained from the PACAP/GHRH gene, the unique DNA sequences occurring at the junction between the vector and the homologous promoter or the homologous TTS may be similarly employed to identify transgenic fish, as these unique DNA sequences will not occur in non-transgenic fish. A suitable primer is made which hybridises to a stretch of DNA spanning the junction between the vector and homologous promoter or the vector and homologous TTS. Comparison of salmon GHRH-like and PACAP peptides with mammalian forms The salmon GHRH-like peptide has sequence similarity not only to the mammalian GHRH, but also to the PRP region of the mammalian PRP/PACAP precursor. The processing sites in the salmon GHRH-like peptide suggest that it is processed to a free acid carboxy terminus like those of carp [11], rat [33,34] and mouse [35,36] GHRH peptides (Fig. 7) . Salmon GHRH-like peptide is identical in length to the carp hypothalamic GHRH [11] and has 91% amino acid sequence identity (Fig. 7) . There is only 40% sequence identity between the salmon GHRH-like peptide and human GHRH (Fig. 7) . Even in mammals, the GHRH family is not highly conserved; rat [33,34] and mouse [35,36] GHRH have only 66% and 61% sequence identity to human GHRH, respectively. A comparison of the first 28 residues of the salmon GHRH-like peptide and human GHRH reveals a 57% sequence identity. The higher conservation of the amide terminus probably reflects the fact that only the first 29 amino acids of the carp and human GHRHs are required for full biological activity. High sequence identity (59%) is also found in the first 28 amino acids between salmon GHRH-like peptide and the mammalian PRPs. No function has yet been shown for the mammalian PRP-29 molecule, but this molecule is processed and secreted from Chinese hamster cells that were transfected with an expression vector containing the human PACAP cDNA [37]. There is also some degree of amino acid sequence identity between salmon GHRH-like peptide and the big PRP region (48 residues) of the PRP/PACAP precursor from sheep (58%) , human (56%) and rat (46%) . Analysis of the untranslated regions in the salmon GHRH/PACAP CDNA The 5' untranslated regions of two clones were different in size and sequence. The size of the 5' untranslated region was 39 bases in clone SS/RACE and 84 bases in clone SS/RACE 7 (Fig. 1) . All clones containing the 5' untranslated region, including these longer clones and two shorter versions (see below) , were identical from nucleotide positions -9 through -1, except for clone SS/RACE 7 which had an adenine at position -4 (Fig. 8) . In common, the 5' untranslated regions have a adenine at position -3, which appears to be required for efficient translation [40,41]. Upstream of position -9, the 5' untranslated regions were completely different in all the clones. Differences in the 5' untranslated region are not unusual and the polymorphisms observed in this study may be due to differences in the regulation of the molecule. IGF I in the rat has different 5' untranslated regions which are connected to an identical precursor coding region [42]. An additional (ATG) codon is present in each of the 5' untranslated regions of two clones (SS/RACE 7 and CS/LIBb, Fig. 8) , but translation from these sites would end at stop codons downstream. However, reinitiation at the next ATG codon would result in an in-frame precursor starting 16 amino acids downstream of the original initiator. Reinitiation in eukaryotic cells requires that the preceding open reading frame is short [41,43]. The 3' untranslated region is shorter in salmon GHRH/PACAP than in the mammalian precursors. Both clones SS/PCR 4 and SS/PCR 5 appeared to be complete because a homopolymeric (dA) tail was present with a putative polyadenylated signal 16 bp upstream. The polyadenylation signal, ATTAAA, is different from the ovine and human AGTAAA. Within the 3' untranslated region, the sequence AATC (624-631 bp. Fig. 9) is repeated in clone 4, occurs only once in clone 5, and is absent in the ovine and human precursors (Fig. 9) . However, the 3' untranslated region of salmon GHRH/PACAP precursor is unique in that it has a high sequence identity (70%) to the mammalian forms (Fig. 9) . Conservation between fish and mammals of 3' untranslated regions in other neuropeptide gene families are usually restricted to only a few motifs [44]. Considering the evolutionary distance between fish and mammals, approximately 400 million years, the high conservation of the 3' untranslated sequence is probably related to the function of the 3' untranslated region in interactions of the mRNA with proteins that affect mRNP structure and translational control [45] . Identification of a short precursor containing only the PACAP region PCR products obtained from screening a chum salmon cDNA library with primers NMS2 combined with SK or KS, were assessed for GHRH/PACAP sequences. Six clones (CS/LIB) were identified that contained a shortened version of the GHRH/PACAP precursor. Four clones had a complete sequence from the NMS2 binding site through to the 5' untranslated region (Fig. 10) . Two different 5' untranslated regions (CS/LIBa and CS/LIBb) were identified from these four clones (Fig. 10) . The remaining two clones were truncated versions of the short precursor. In all CS/LIB clones the short precursor was formed by a deletion of 105 nucleotides at positions 234- 338 the coding region for GHRH, leaving the PACAP coding region in a correct reading frame (compare Fig. 1 with 10) . Five of the short precursor CS/LIB clones were found to contain an adenine at position 232 like that of the longer form of clone SS/RACE 7 (compare Fig. 1 with 10) . This results in a change in the reading frame of the short precursor to a serine at amino acid position 78 (Fig. 10) . Following position 78 in the short precursor, the reading frame then skips to position 114 of the longer GHRH/PACAP precursor and remains unchanged. Clone SS/RACE 2 has a guanine at position 232, which results in the triplet codon for glycine. Analysis of other clones from the RACE reaction (SS/RACE) also showed two clones that contained the same short precursor form as the CS/LIBa and b. Although these clones were identical in respect to the region deleted (bp positions 234-338) , they had several nucleotide substitutions resulting in three amino acid changes (data not shown) . The site of the deletion, which corresponds exactly to exon 4 of the gene, is shown in Figure 10. Exon 4 encodes GHRH^**. and three amino acids in the carboxy terminal portion of the cryptic peptide. The PACAP region is not shown, but is deduced from the fact that a specific primer made to PACAP (NMS3) was used to synthesize single stranded cDNA to obtain the short precursor. The detection of a short precursor that contains only PACAP is of considerable interest in a functional sense. The fact that this short precursor form was obtained from both the RACE reaction of sockeye salmon mRNA and from the chum salmon cDNA library suggests it is not a cloning artifact. The short precursor form may have been due to problems of secondary structure in the mRNA during the reverse transcriptase reaction but, it is also possible that the short precursor was generated by differential post-transcriptional processing. Our partial sequence analysis of the salmon gene shows this short precursor may be the product of alternate processing of the mature mRNA (unpublished results) . The region excised in the short cDNA precursor corresponds to a single exon containing the last 3 amino acids of the cryptic peptide and the first 32 amino acids of the GHRH- like molecule. The two exons encoding the cryptic peptide and PACAP are joined, resulting in a shorter mRNA that only codes for PACAP. Shorter transcript forms have been, observed for another member of the glucagon superfamily; different transcriptional processing of secretin RNA results in the loss of exon three and a shorter precursor [46]. In the present study, cell specific processing of both precursors may have occurred in the brain since the source of the mRNA for the library and the RACE reaction was obtained from whole salmon brains. It is also possible that the shorter precursor is transcribed from a different gene with different regulatory elements. Deduction of polymorphism and gene copy number Four salmon GHRH/PACAP clones were identified that had nucleotide differences. The sequence heterogeneity of the coding and 3' untranslated regions between these two clones was greater than the expected error rate of Taq polymerase [47,48]. These clones may represent allelic polymorphisms or separate non-allelic genes. Salmonids are known to be tetraploid. Furthermore, an indication of more than one gene copy for the GHRH/PACAP precursor was observed in a Southern blot of sockeye salmon genomic DNA hybridized with a 355 bp probe which included the GHRH and PACAP coding regions and 91 bp of the 3' untranslated region. Restriction enzyme digests demonstrated that different allelic forms or genes are present. . Other members of the glucagon superfamily may be represented in bands that were easily removed by high stringency washes. In fish there are other examples in which differences in nucleotide sequence in the coding and 3 ' untranslated regions have been reported between two genes that code for the same hormone: melanin- concentration hormone [50,51], proopiomelanocortin [52], and corticotropin-releasing factor [44]. Expression of GHRH/PACAP mRMAs Northern blots were done with a 588 bp probe that was amplified from the full length cDNA clone. Two bands were detected in sockeye salmon and Chinook salmon brain poly(A) + - rich mRNA, one band ranging from 2.5 to 2.8 Kb and the other from 0.7 to 1.0 Kb. The band width suggested that mRNAs of varying length were present. The size of the larger salmon mRNA detected by Northern blot is in the same size range (3 Kb) as the rat, human, and ovine cDNAs. However, the 5' untranslated regions of the salmon GHRH/PACAP cDNAs are much shorter than the same region of other GHRH [35,53,54] and PACAP cDNAs [1,8,9] suggesting these salmon GHRH/PACAP clones may be incomplete. The length of the 5' untranslated region is unknown in any of the PACAP cDNAs, although it is at least 500-600 bp in rat and sheep. The 3' untranslated region in the mammalian cDNAs is estimated to be 1400-1600 bp. This 3' untranslated region is quite different in length compared to 146 bp in the 3' untranslated region of the salmon. The rat VIP/PHI gene, which has high sequence identity to the PACAP gene, produces two different sizes mRNAs, a rare one with a 3' untranslated region of 100 base pairs and an abundant one of 800 bp [5]. The size of the small band (0.7-1.0 Kb) of salmon mRNA detected by Northern blot agrees with the size of the cDNA clone (0.73 Kb). The length of the 5' and 3' untranslated regions is not important for use of the salmon cDNA for preparation of recombinant proteins or constructs for transgenic fish as this region may be supplied by the construct cassette. The similarity between salmon GHRH-like peptide and the mammalian GHRHs is also indicated by the type of amino acid in positions known to be important for biological activity in mammalian GHRHs. The N-terminal amino acid in the seven mammalian GHRHs reported to date is a hydrophobic residue, either Tyr or His (35,68). Substitution or modification of this initial Tyr or His in mammalian GHRHs has been shown to reduce potency drastically. The N-terminal amino acid of salmon, sturgeon and possibly catfish GHRH-like peptide is His (38,72) . PACAPs, which also release GH, also have His as the N-terminal amino acid in both fish and mammals. In contrast, mammalian PRPs all have Asp as N- terminal amino acid. As will be understood by those skilled in the art, DNA molecules comprising a number of nucleotide sequences are capable of encoding the precursor proteins and polypeptides of this invention, due to the degeneracy of the genetic code. The present invention includes both the nucleotide sequences specifically set out herein and all degeneracy equivalents or DNA molecules comprising nucleotide sequences which encode the same amino acid sequences as the specific nucleotide sequences. The invention also includes portions of these nucleotide sequences, and analogs of these nucleotide sequences which encode polypeptides retaining the biological activity of the polypeptides described herein or encode precursor proteins which are precursors of polypeptides retaining the biological activity of the polypeptides described herein. These are referred to herein as "effective portions" or "effective analogs". The amino acid sequences of the precursor proteins and polypeptides of the invention may be modified by conservative additions, deletions and/or substitutions while retaining the biological activity of these molecules, as will be understood by those skilled in the art. Such modified amino acid sequences are included within the scope of this invention and are referred to herein as "effective variants". Additionally, fragments or portions of the precursor proteins and polypeptides of the invention may retain biological activity and such fragments are included in this invention. They are referred to herein as "effective fragments". It will be understood by those skilled in the art that variants or fragments of the polypeptides of the invention which retain biological activity may display higher or lower biological activity than the specifically described polypeptides. The following examples are illustrative only and are not to be construed as limiting the invention. EXAMPLES Example l - sockeye salmon cDMA 1.1 mRNA purification and cDMA synthesis Sockeye salmon fOncorhynchus nerka) were anesthetized with carbon dioxide and the brains were immediately excised and frozen in liquid nitrogen. Total RNA was isolated from sockeye salmon brains by extraction with acidic guanidinium thyiocyanate according to Chomczynski and Sacchi [27]. Poly (A) + mRNA was purified by oligo (dT) affinity chromatography (Pharmacia LKB Biotechnology) . Double stranded cDNA was synthesized from 5 μg of poly (A) + mRNA using Stratagene's cDNA synthesis kit. 1.2 Amplification of cDMA PCR samples were each prepared in a 100 μl volume containing 10 μl of double stranded cDNA, 100 pmol of primer CSC 33, 100 pmol of adaptor GAATTCT(dT) 36, 10 mM Tris-HCl (pH 8.3), 50 mM KC1, 0.01% gelatin, 0.05% NP 40, 0.05% Tween 20, 1.5 mM MgCl 2 , 200 μM dNTPs and 2.5 units of Taq DNA polymerase (Perkin-Elmer Cetus) . DNA was amplified using a step program of 1 cycle at 94°C for 3 min, 55°C for 2 min, and 72°C for 4 min, followed by 29 cycles of 94 β C for 1 min 30 s, 55 β C for 2 min and 72 β C for 4 min (DNA Thermal Cycler, Perkin-Elmer Cetus) . The last cycle had an 8 min extension at 72°C. Ten microliters of PCR product was removed and reamplified under the same conditions. PCR products were separated by electrophoresis on a 2.0% agarose gel (Bio 101) and the cDNA bands recovered by binding to Glassfog™ using MERmaid (Bio 101) . 1.3 Amplification of the 5'end We used the rapid amplification of cDNA ends (RACE) strategy designed by Frohman et al. [28], with minor modifications to amplify the 5'end. Two microliters of sockeye salmon poly (A) + mRNA (0.344μg/μl) was mixed with 10 pmol of NMS 3 primer and 7 μl of DEPC treated water to a final volume of 10 μl, heated at 65°C for 3 min then cooled rapidly on ice. Single stranded cDNA was made by adding 10 μl of reverse transcriptase solution (4 μl 5X BRL buffer (250 mM Tris-HCl, 375 MM KCl, 15 mM MgCl 2 ) , 2 μl 0.1 M DTT, 2 μl 10 mM dNTP's, 1 μl RNA guard (Pharmacia LKB Technology) , and 1 μl M-MLV K RT (Superscript, BRL)) to the mRNA/primer mix and incubating for 2 h at 41°C. The reaction was stopped by heating to 75 β C for 10 min, then diluted to 500 μl with TE pH 7.5 and stored at 4°C. The primer was removed from the reaction mixture by centrifugation through a centricon- 100 (A icon) twice with 0.2X TE pH 7.5. First strand cDNA was vacuum concentrated to 12.5 μl, of which 10 μl was tailed with dATP at 37 β C for 5 min in 4 μl 5X BRL buffer, 4 μl 1 MM dATP, 1 μl water and 1 μl TdT enzyme (BRL) . The reaction mixture was heat denatured 5 min at 70°C and diluted to 200 μl with sterile water. The remaining 2.5 μl of first strand cDNA was sham tailed (no enzyme) under the same conditions. Polymerase chain reactions were done in 50 μl volumes containing 20 pmol of primer NMS 1, 20 pmol of adaptor ≠3(GGCTCGAGCCCGGGAATTCCG) , 5 pmol of adaptor ≠2(GGCTCGAGCCCGGG AATTCCG-dT 15 ) , IX Promega buffer (50 mM KCl, 10 mM Tris-HCl, 0.1% Triton X-100) , 2.0 mM MgCl 2 , 200 μM dNTP's, and 2.5 units of Taq DNA polyermase (Promega Corp. , Madison, WI) . In the first round of the PCR a 5 μl aliquot of dATP tailed cDNA was amplified using a step program for 30 cycles (DNA Thermal Cycler, Perkin-Elmer Cetus) . In the first cycle the DNA was denatured at 94°c for 3 min, annealed at 60°C for 2 min and extended at 72°C for 8 min. The following 29 cycles were 94 β C, 58°C and 72°C, all at 1 min intervals except for a final 8 min extension at 72°C. The PCR products were separated on a 1.5% agarose gel (SeaKem, FMC BioProducts) and the DNA bands electroeluted in dialysis tubing (Spect/Por, Spectrum Medical Ind. , Inc.) with IX TAE. Three microliters of this DNA was reamplified using primers NMS1 and adaptor #3 with a lower annealing temperature and more cycles (1 cycle at 94°C, 3 min; 55°C, 2 min; 72°C, 5 min; 41 cycles at 94°C, 1 min; 55 β C, 1 min; 72°C 1 min) . The PCR amplified DNA was extracted, gel purified and electroeluted as previously. Another strategy used to determine the 5' end of the GHRH/PACAP precursor, was to use the PCR to screen a chum salmon cDNA library prepared in lambda ZAP II (Stratagene, La Jolla, CA) . To amplify the 5' end, primer NMS 1 in combination with primer SK or KS (Stratagene) were used in the first round of the PCR (1 cycle at 94 β C for 3 min, 45 β C for 2 min, 72 β C for 10 min; 41 cycles at 94 β C for 1 min, 45 β C for 2 min, 72 β C for 2 min; the last cycle had an 8 min extension at 72°C) . The PCR products were separated on a 2% agarose gel (Seakem) and the DNA bands retrieved as previously described. One fifth of this DNA was then reamplified with primers NMS2 and SK. The NMS2 primer was selected because it is internal to NMS1 and hence is specific for the region desired for amplification. 1.4 DMA cloning DNA obtained from the PCR was blunt end ligated into pBluescript II KS+ (Stratagene) , which had been cut with EcoR V and dephosphorylated. The PCR products were blunt ended and kinased in IX ligase buffer (50 mM Tris-HCl pH7.6, 10 mM MgCl 2 , 5% polyethylene glycol-8000) , 1 mM ATP and 200 μM dNTP's. Klenow polymerase (Pharmacia) was added and the reaction mixture incubated at 12°C for 1 h, followed by the addition of T4 PNK (Pharmacia) and an incubation at 37°C for 45 min. The reaction mixture was heat denatured at 75°C for 15 min, then placed on ice. The cDNA was blunt end ligated into pBluescript II at 22°C for 16-18 h by the addition 1 μl 5X ligase buffer, 2 μl 100 mM DTT, 0.5 μl 10 mM ATP, 0.5 μl vector and 1 unit of T4 ligase (BRL) . Recombinant plasmids were identified by blue and white selection in XL-1 blue cells (Stratagene) . Miniprep plasmid DNA was prepared by the alkaline hydrolysis method (29) and digested with Pvu II to identify plasmids with inserts. Recombinant plasmids were then screened by the PCR using primers CSC 33 and NMS 1 to identify clones containing the GHRH-like cDNA. 1.5 Sequencing Single and double stranded cDNA inserts were sequenced by the chain termination method [30] using 35 S- dATP (Dupont) and Sequenase Version 2.0 according to the manufacturer's instructions (US Biochemical Corp., Cleveland, OH) . 1.6 Southern Blot Sockeye salmon genomic DNA (24 μg) was digested with either Hae III, Hind III, Pst I, or EcoR I and electrophoresed on a 1% agarose gel. DNA was capillary transferred to Zeta probe nylon membrane (Bio-Rad) and prehybridized in aqueous buffer [31] at 60°C for 3 h. The probe used in the hybridization was a 355 bp cDNA cut with MSE I and labelled with 3 P-dCTP (Dupont) by random priming (5.6 X 10 6 cpm/ml) . The filter was washed twice in 2X SSC/O.1% SDS for 15 min at room temperature, then twice in IX SSC/0.1% SDS for 15 min at 60°C and twice again in IX SSC/O.1% SDS for 10 min at 60°C prior to autoradiography. 1.7 Northern Blot Northern blots and hybridization conditions were done according to Ausubel et al. [32]. Ten micrograms of salmon brain poly (A) + mRNA and 56 μg of salmon brain total RNA was electrophoresed on a formaldehyde denaturing agarose gel in IX MOPS running buffer. RNA was capillary transferred with 10X SSC to a Zeta probe nylon membrane (Bio-Rad) . The membrane was baked for 2 h at 80 β C and then prehybridized for 4 h at 42 β C with 15 ml of hybridization buffer (6X SSC/50% formamide/0.1% Tween 20/100 μg'ml' 1 denatured urchin sperm DNA) in a sealed plastic bag. The membrane was hybridized with a 588 bp cDNA probe 18-20 h at 42°C in hybridization solution. The cDNA probe was made by amplification of the salmon GHRH/PACAP clone using primers SPl (5'GGAATCATAATGCACTACA GTGTC 3') and NMS5 (5'GAACACAAGAGCGATCCACTGA 3':Sequence ID No: 17) , and labelled with 32 P-dCTP by random priming. Example 2 - Synthesis and characterization of salmon GHRH and PACAP Salmon GHRH and PACAP were synthesized on a Beckman 990 synthesizer using classical solid phase peptide synthesis techniques [73, 74]. In brief, these peptides were assembled on 4 g of a BocSer(Bzl) chloromethyl resin using Boc amino acids with the following side protecting groups: Lys(2-Cl-Z), Thr(Bzl) , Glu(0-7-cyclohexyl) , Ser(Bzl), Asp(O-jScyclohexyl) , Arg(Tos) , His(Tos), and Tyr(2Br-Z). Hydrogen fluoride cleavage and deprotection at 0°C in the presence of anisole as a carbocation scavenger was followed by (a) removal of the HF and unreacted anisole under vacuum, (b) treatment with anhydrous ethyl ether to remove residual HF, anisole, and their derivatives, and (c) extraction with aqueous HOAc and lyophilization to yield the crude peptidic preparations. Purification was accomplished using HPLC techniques. The composition of the final purified products was determined by amino acid analysis. E -wni i* 3 - Biological activity of salmon GHRH-like peptide and PACAP Coho salmon pituitaries were removed and placed in sterile Hank's medium. Standard in vitro methods were used to prepare dispersed cells. Synthetic peptides were diluted in Hank's medium to the concentrations shown in Fig. 11. A concentration of 10" 7 M only was used in the time course study (Fig. 12) . The peptides were added to the culture dishes on the 4th day of incubation. On the 5th day, the medium was collected and assayed for GH using a radioimmunoassay specific for salmon GH. Example 4 - Catfish cDMA 4.1 mRNA purification and cDNA synthesis Brains were removed from Catfish (Clarias macrocephalus) . The brains were immediately frozen in liquid nitrogen. The mRNA was isolated and cDNA synthesised as described for sockeye salmon in Example 1.1., 4.2 Preparation of a cDNA library plate lysate A cDNA library, prepared with Lambda Zap II (Stratagene) and Gigapack Gold packaging mix (Stratagene) was used to prepare a lysate with the following procedure. Twelve plates (150x10mm) of FRM bottom agar (5%NaCl, 2%MgCl 2 -6H 2 0, 10% NZ a ine, 3% yeast extract, 2% casamino acids, 2% maltose and 14% agar) were covered with 8 mis FRM top agarose, 200μl XL-1 cells and phage diluted to a density of 50,000 plaque forming units (pfu) per plate. The phage were grown (37°) until confluent lysis of the XL-1 cell lawn had occurred. Then, 10 ml of SM buffer was layered on top to swirl gently overnight. The next morning the SM buffer was removed and 5 ml of new SM buffer was added. After 3 hours of shaking, the SM buffer was removed, pooled with the initial wash and stored in a sealed glass bottle with a few drops of chloroform. The plate lysate was prepared from 10 ml of the SM buffer wash which was spun (10,000g, 10 minutes) to pellet any bacterial material. After lOμl RNaseA (Sigma, boiled, lOmg/ml) and 25 μg of crude DNase I (Sigma) were added, the contents were vortexed well and incubated at 37°C for 30 minutes. Following centrifugation (10,000g, 10 minutes) the supernatant was removed and an equal volume of precipitating solution (2.5M NaCl, 20% polyethylene glycol) was added. The solution was allowed to precipitate on ice for 1.5 hr, then spun at log for 20 minutes. The supernatant was removed; the pellet was hydrated in 400μl of IX proteinase K buffer (0.2% sodium dodecyl sulfate (SDS), lOOmM Tris pH 8, 150mM NaCl, lOmM EDTA) . The hydrated pellet was combined with 20 mg proteinase K (BRL) , incubated at 50° for 30 minutes, and extracted with two equal volumes of a solution containing one part of phenol(buffered) with one part of chloroform:isoamyl (24:1). These washes were then followed by two chloroform:isoamyl (24:1) washes. The mixture was spun (5,000g, 5 minutes). The top layer was removed and 3M sodium acetate (final concentration of 0.3M) and 3 volumes of 100% ethanol were added. 4.3 Polymerase chain reaction (PCR) of purified library CDNA The DNA amplification involved the nondegenerate primers, SPl, NMS3, and NMS4, made against the salmon GHRH-PACAP cDNA sequence. The first DNA amplification in the DNA Thermal Cycler (Perkin-Elmer Cetus) , was in a 50μl volume (2μ] cDNA, 5μl lOx Taq buffer (Promega), 8μl 1.25mM dNTP's (Pharmacia) , 1 μl 20μM SP 1 primer, 1 μl 20 μM NMS3 primer, 32.5 μl H20, and 0.5μl Taq enzyme (Promega)). This solution was layered with 50μl of mineral oil (Sigma), and cycled 35x, each cycle included steps at 94° for 1.5 minutes, 45° for 2 minutes, and 72° for 2.5 minutes with an extension period of 5 minutes and 16 seconds at 72°. Once the cycles were complete, the reaction mixture was combined with 50μl chloroform (BDH) , vortexed and spun at 10,000g for 10 minutes. The top layer was removed and precipitated overnight with 5μl of 3M sodium acetate and 2 volumes of 100% ethanol. The DNA solution was loaded onto an ethidium bromide stained 1.5% SeaKem gel and run until the bands were well separated. Four individual bands were cut out and separately electroeluted within dialysis bags (40mAmps, 1.5 hours). This solution was precipitated overnight. The precipitated DNA was pelleted (10,000g, 25 minutes), washed with 180μl 75% ethanol and hydrated in lOμl H 2 0. This DNA solution was used for the second PCR amplification in a 50μl reaction (lOμl DNA/H20, 5μl lOx TAQ buffer, 8μl 1.25nM dNTP, lμl 20μM SPl primer, lμl 20μM NMS3 primer, 24.5 μl H 2 0, and 0.5 μl TAQ DNA polymerase) using 35 cycles with steps of 94°(1.5minutes) , 50°(2minutes) , and 72°(2.5minutes) plus an extension of 5 minutes and 16 seconds at 72°. Once completed, 5μl of the reaction was removed directly from the PCR tube, combined with 5μl of water and 2μl of 6X loading buffer. The DNA mixture was loaded onto a 1.5 SeaKem gel (ethidium bromide stained) and electrophoresed one hour. Four sets of bands appeared under ultraviolet light but only three bands were considered large enough. Therefore, the three bands 2, 3, and 4, were cut out and electroeluted (45m Amps, lhr) in dialysis bags. 4.4 DNA cloning Bands #2, #3, and #4, electroeluted and precipitated as described above, were cloned as described in Example 1.4. 4.5 Sequencing Sequencing was done as described in Example 1.5. 4.6 cDNA Library Screening For library screening the partial (393 bp) GHRH- PACAP cDNA clone was cut from KS-Bluescript with Not 1 (Pharmacia). The insert was electrophoresed on a 1.5% gel, cut out and electroeluted. Library phage dilutions of 10 "2 , 10" 4 , 10" 5 , and 10 " * were individually (5μl) combined in a 15ml 2059 Falcon tube with 45μl SM buffer and lOOμl XL-1 cells. The tubes were incubated 5 minutes at room temperature followed by 15 minutes at 37°. Molten (50°) FRM-agarose (3ml) was added to the tube and the contents, poured over the FRM- agar plate (100x15mm) . The plates were incubated 10-12 hours at 37°. For first round screening, two nylon membranes (DuPont) per plate were labelled "A" and B". The A filters were laid on the agarose, for two minutes, then placed into 1 liter (L) of denaturing solution (1.5M NaCl, 0.5M NaOH) for 10 minutes. The filters were transferred to 1L of neutralizing solution (1.5M NaCl, 0.5M Tris-HCl pH 8) , swirled 10 minutes and placed again in fresh neutralizing solution. The filters were transferred to 1L 2X SSC, swirled 5 minutes, transferred to fresh 2X SSC and agitated for another 5 minutes. The filters were removed and left to dry at room temperature. The B series membranes were put on the plates, left for 5 minutes, removed and placed in denaturing solution. The remaining procedure for the B filters was the same as for the A filters. All filters were combined, baked at 80° for 2 hours, and stored in a dessicator. Prior to prehybridization the filters were placed one at a time into 6X SSC for 10 minutes. The 6X SSC was removed and 100ml prehybridization solution (6XSSC, 5X Denhardt's solution, 0.5%SDS and 30μg/ml boiled sea urchin DNA) was added and incubated with shaking for 4 hours at 50°. Labelling the GHRH probe followed the Vogelstein labelling method. To determine the labelling efficacy 2μl was removed. The prehybridization solution was removed and 100ml hybridization solution (6X SSC, + No. 5X Denhardt's solution 0.5%SDS, and 30μg/ml boiled sea urchin DNA) was added to the filters. The labelled probe was boiled (10 minutes) , quenched on ice, and combined with the hybridization solution. The filters were incubated overnight at 50°. The hybridization solution was decanted and stored at -20° for the second round. Filters were washed with increasingly higher stringency starting with 2XSSC- 0.1%SDS at 50° (45min) and ending with 0.1XSSC-0.1%SDS at 65°(45 min). The filters were air dried and placed with film to develop for 7 days at -80°. Autoradiograms were then developed. Postives were aligned against the original plate; the plaque of interest was cored and placed with 1.5ml SM buffer and 20μl chloroform. The mixture was left overnight at 4°. 4. in Vitro Excision Once a single positive plaque was isolated, an in vitro excision was done to allow isolation of the plasmid cDNA. Combined were 200μl XL-1 cells (00( 00 =1.0), 200μl lambda Zap II phage (isolated core) , and lμl R408 helper phage. The mixture was incubated at 37° for 15 minutes and 2X YT media (5ml) was added. The mixture was incubated 3 hours at 37° with vigorous shaking, heated to 70° for 20 minutes and spun 5 minutes at 4,000g. The pBluescript supernatant was removed and stored at 4°. 4.8 Northern Blot An agarose/formaldehyde gel (4.2g agarose, 304.5ml water, 35ml 10X MOPS, 10.5ml formaldehyde) was prepared for the Northern analysis. Thai catfish total RNA (20μg) and a RNA ladder (4μg) were loaded as molecular weight markers. The markers and another sample of total RNA (20μg) , Thai catfish poly A+ mRNA (lOμg) and African catfish Poly A+ mRNA (lOμg) were each mixed with 5μl 10X MOPS, 8.75μl 37% formaldehyde, and 25μl formamide. The tubes were incubated 15 minutes at 55°. Loading buffer (lOμl) (lmM EDTA, 0.25% Bromophenol blue, 0.25% Xylene Cylanol, and 50% glycerol) was added to the RNA and loaded onto the gel. The gel was run at 100 volts for 3 hours. The part of the gel with the two lanes of total RNA and RNA markers was cut from the rest of the gel and stained with an ethidium bromide solution (25μl of lOmg/ml in 500ml) for 45 minutes. The remaining piece was washed several times with water (10 minutes each) and one wash of 10XSSC for 45 minutes. A transfer pyramid was set up according to the Sambrook (1989) protocol using a Bio-Rad Zeta probe membrane and left overnight in 10X SSC. The pyramid was disassembled the next morning the membrane was air dried and baked at 80° for 2 hours. Once baked, the membrane was placed into a small bag with 10ml Northern prehybridization solution (25mM KP04, 5X SSC, 10X Denhardts, 50% formamide, and 30μg/ml sea urchin sonicated DNA) and incubated overnight at 40°C. The prehybridization solution was removed and 10ml hybridization solution (same as prehybridization solution plus 5% dextran sulfate) and the probe were added. Hybridization was continued overnight at 40°C. Washes with stringency similar to those used for the filter lifts were used to clean the membrane. Once air dried, the filter was placed into a cassette, with amplifying screens, and stored at -80° overnight. Example 5 - Sturgeon cDNA 5.1 mRNA purification and cDNA synthesis White sturgeon fAcipenser transmontanus-) brains were excised and immediately frozen in liquid nitrogen. Total RNA was isolated from these brains by extracting with acidic guanidium thiocyanate, according to Chomczynski and Sacchi (27) . Poly A+ mRNA was purified by oligo-dt affinity chromatography (Pharmacia LKB Biotechnology) . Single stranded cDNA was synthesized from 2 μg of poly A+ mRNA, using reverse transcriptase PCR technology and the sequence specific downstream primer, NMS 3. 5.2 Amplification of cDNA PCR samples were each prepared in a 100 μl volume containing lOμl of single stranded cDNA, 50 pmol of primer SPl, 50 pmol of primer NMS3, 2.5 units of Taq DNA polymerase (Promega), 1.5mM MgCl 2 , 200 μM dNTPs and 10 μl lOx Taq polymerase buffer (Promega) . DNA was amplified using a step program of 1 cycle at 94°C for 1.5 min., 55 β C for 2 min., and 72 β C for 6 min, followed by 35 cycles of 94 β C for 1.5 min, 54 β C for 2 min. and 72 β C for 3 min. (Perkin-Elmer Cetus) . The last cycle had a 6 min. extension at 72°C. PCR products were separated by electrophoresis on a 1.5% agarose gel (FMC -SeaKem), recovered by electroelution and cloned and sequenced as in Example 1.4 and 1.5, respectively. The present invention is not limited to the features of the embodiments described herein, but includes all variations and modifications within the scope of the claims. TABLE I AMINO ACID SEQUENCE IDENTITY OF CATFISH AND STURGEON GHRH/PACAP PRECURSORS COMPARED TO THE SALMON PRECURSOR signal cryptic GHRH-like PACAP PACAP peptide peptide -27 -38 salmon 100 100 100 100 100 catfish 68 48 62 78 61 sturgeon — 77 84 — — TABLE II AMINO ACID SEQUENCE IDENTITY OF FISH GHRH/PACAP PRECURSORS COMPARED TO THE HUMAN PACAP PRECURSOR signal cryptic GHRH-like PACAP PACAP peptide peptide \PRP -27 -38 human 100 100 100 100 100 salmon 77 36 56 100 92 catfish 52 26 42 78 61 sturgeon — 43 54 — — REFERENCES 1. Ohkubo, S., Kimura, C, Ogi, K. , Okazaki, K. , Hosoya, M. , Onda, H. , Miyata, A., Arimura, A., & Fujino, M. (1992) Primary structure and characterization of the precursor to human pituitary adenylate cyclase activating polypeptide, DNA Cell Biol. v. 11, pp. 21-30. 2. 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Claims: We claim: 1. An isolated DNA molecule comprising a nucleotide sequence encoding fish PACAP and GHRH-like peptide. 2. A DNA molecule in accordance with claim 1 wherein the nucleotide sequence encodes salmon PACAP and GHRH-like peptide, said nucleotide sequence comprising nucleotides -39 to 668 of Figure 1 (Sequence ID NO :1) or a degeneracy equivalent or an effective portion or analog thereof. 3. A DNA molecule in accordance with Claim 1 wherein the nucleotide sequence encodes catfish PACAP and GHRH-like peptide, said nucleotide sequence comprising nucleotides -321 to 2181 of Figure 2 (Sequence ID NO : 2) or a degeneracy equivalent or an effective portion or analog thereof. 4. An isolated DNA molecule comprising a nucleotide sequence corresponding to nucleotides l to 339 of Figure 3 (Sequence ID NO : 3) or a degeneracy equivalent or an effective portion or analog thereof. 5. An isolated DNA molecule comprising a nucleotide sequence encoding fish GHRH-like peptide. 6. A DNA molecule in accordance with claim 5 wherein the nucleotide sequence encodes salmon GHRH-like peptide, said nucleotide sequence comprising nucleotides -39 to 378 of Figure 1 or a degeneracy equivalent or an effective portion or analog thereof. 7. A DNA molecule in accordance with claim 5 wherein the nucleotide sequence encodes salmon GHRH-like peptide 28, said nucleotide sequence comprising nucleotides -39 to 327 of Figure 1 or a degeneracy equivalent or an effective portion or analog thereof. 8. A DNA molecule in accordance with claim 5 wherein the nucleotide sequence encodes catfish GHRH-like peptide, said nucleotide sequence comprising nucleotides -321 to 381 of Figure 2 or a degeneracy equivalent or an effective portion or analog thereof. 9. A DNA molecule in accordance with claim 5 wherein the nucleotide sequence encodes catfish GHRH-like peptide 45, said nucleotide sequence comprising nucleotides -321 to 381 of Figure 2 or a degeneracy equivalent or an effective portion or analog thereof. 10. - An isolated DNA molecule comprising a nucleotide sequence encoding fish PACAP. 11. A DNA molecule in accordance with claim 10 wherein the nucleotide sequence encodes salmon PACAP, said nucleotide sequence comprising nucleotides -51 to 390 of nucleotide sequence A of Figure 10 (Sequence ID NO : 4) or a degeneracy equivalent or an effective portion or analog thereof. 12. A DNA molecule in accordance with claim 10 wherein the nucleotide sequence encodes salmon PACAP, said nucleotide sequence comprising nucleotides -44 to 390 of nucleotide sequence B of Figure 10 (Sequence ID NO : 5) or a degeneracy equivalent or an effective portion or analog thereof. 13. A DNA molecule in accordance with claim 10 wherein the nucleotide sequence encodes salmon PACAP 27, said nucleotide sequence comprising nucleotides -51 to 357 of nucleotide sequence A of Figure 10 or a degeneracy equivalent or an effective portion or analog thereof. 14. A DNA molecule in accordance with claim 10 wherein the nucleotide sequence encodes salmon PACAP 27, said nucleotide sequence comprising nucleotides -44 to 357 of nucleotide sequence B of Figure 10 or a degeneracy equivalent or an effective portion or analog thereof. 15. A fish PACAP and GHRH-like peptide precursor protein. 16. A precursor protein in accordance with claim 15 comprising a salmon PACAP and GHRH-like peptide precursor protein wherein the amino acid sequence comprises the amino acid sequence of Figure 1 (Sequence ID NO : 6) or an effective variant or fragment thereof. 17. ' A precursor protein in accordance with claim 15 comprising a catfish PACAP and GHRH-like peptide precursor protein wherein the amino acid sequence comprises the amino acid sequence of Figure 2 (Sequence ID NO : 7) or an effective variant or fragment thereof. 18. A fish PACAP precursor protein. 19. A protein in accordance with claim 18 comprising a salmon PACAP precursor protein wherein the amino acid sequence comprises amino acid 1 to amino acid 131 of Figure 10 (Sequence ID No: 10) or an effective variant or fragment thereof. 20. A fish GHRH-like peptide precursor protein. 21. A protein in accordance with claim 20 comprising a salmon GHRH-like peptide precursor protein wherein the amino acid sequence comprises amino acid 1 to amino acid 126 of Figure 1 or an effective variant or fragment thereof. 22. A protein in accordance with claim 20 comprising a catfish GHRH-like peptide precursor protein wherein the amino acid sequence comprises amino acid 1 to amino acid 127 of Figure 2 or an effective variant or fragment thereof. 23. A protein in accordance with claim 20 comprising a sturgeon GHRH-like peptide precursor protein wherein the amino acid sequence comprises amino acid 1 to amino acid 105 of Figure 3 or an effective variant or fragment thereof. 24. A substantially pure fish GHRH-like peptide prepared by chemical, enzymatic or recombinant synthesis. 25. A substantially pure fish PACAP peptide prepared by chemical, enzymatic or recombinant synthesis. 26. A substantially pure polypeptide having the amino acid sequence (Sequence ID NO : 8) : His Ala Asp Gly Met Phe Asn Lys Ala Tyr Arg Lys Ala Leu Gly Gin Leu Ser Ala Arg Lys Tyr, Leu His Ser Leu Met Ala Lys Arg Val Gly Gly Gly Ser Thr Met Glu Asp Asp Thr Glu Pro Leu Ser-OH or an effective variant or fragment thereof. 27. A substantially pure polypeptide having the amino acid sequence (Sequence ID NO : 9) : His Ser Asp Gly lie Phe Thr Asp Ser Tyr Ser Arg Tyr Arg Lys Gin Met Ala Val Lys Lys Tyr Leu Ala Ala Val Leu Gly Lys Arg Tyr Arg Gin Arg Tyr Arg Asn Lys-NI^ or an effective variant or fragment thereof. 28. A polypeptide in accordance with claim 26 wherein the polypeptide is a synthetic or recombinant polypeptide. 29. A polypeptide in accordance with claim 27 wherein the polypeptide is a synthetic or recombinant polypeptide. 30. A polypeptide wherein the amino acid sequence comprises amino acid 83 to amino acid 127 of Figure 2 or an effective variant or fragment thereof. 31. A polypeptide wherein the amino acid sequence comprises amino acid 130 to amino acid 168 of Figure 2 or an effective variant or fragment thereof. 32. A polypeptide wherein the amino acid sequence comprises amino acid 61 to amino acid 105 of Figure 3 or an effective variant or fragment thereof. 33. A host transformed with a DNA molecule in accordance with claim 2. 34. A host transformed with a DNA molecule in accordance with claim 3. 35. A host transformed with a DNA molecule in accordance with claim 4. 36. A method for producing fish PACAP and GHRH-like peptide comprising the steps of culturing a host in accordance with claim 33 and recovering the peptides from the culture either in the form of mature peptides or in the form of a precursor protein. 37. A DNA construct comprising a DNA molecule in accordance with claim 1 operatively associated with a suitable promoter and a suitable transcription termination sequence. 38. A DNA construct in accordance with claim 37 wherein the promoter and the transcription termination sequence are from fish. 39. A DNA construct in accordance with claim 37 wherein the DNA molecule comprises a DNA molecule in accordance with claim 2. 40. A DNA construct in accordance with claim 37 wherein the DNA molecule comprises a DNA molecule in accordance with claim 3. 41. A transgenic fish having incorporated into its genome a DNA construct in accordance with claim 39. 42. ■ A transgenic fish having incorporated into its genome a DNA construct in accordance with claim 40. 43. A method for producing enhanced growth of a fish comprising introducing into fertilised eggs of the fish a DNA construct in accordance with claim 39, whereby expression of the DNA construct during growth of the eggs into fish produces PACAP and GHRH-like peptide and gives enhanced growth of the fish. 44. A method for producing enhanced growth of a fish comprising introducing into fertilised eggs of the fish a DNA construct in accordance with claim 40, whereby expression of the DNA construct during growth of the eggs into fish produces PACAP and GHRH-like peptide and gives enhanced growth of the fish. 45. A method for identifying a transgenic fish containing a DNA construct comprising a transfected DNA flanked by at least one heterologous DNA sequence comprising the steps of obtaining a sample of DNA from said fish; amplifying the DNA of the sample by PCR using at least one primer DNA sequence hybridisable to a portion of the DNA construct in the region of the junction between the transfected DNA and the at least one heterologous DNA sequence; and detecting said amplified DNA which is indicative of a transgenic fish.

Inventors: LESCHEID DAVID WILLIAM, MCRORY JOHN EDWIN, PARKER DAVID BERNARD, SHERWOOD NANCY GAIL MCKEOWN, LESCHEID, DAVID, WILLIAM, MCRORY, JOHN, EDWIN, PARKER, DAVID, BERNARD, SHERWOOD, NANCY, GAIL, MCKEOWN
Applicants: UNIV VICTORIA INNOVAT DEV, UNIVERSITY OF VICTORIA INNOVATION AND DEVELOPMENT
Application year: 1994
Main classification: C12N15
IPC codes: A61K38, C07K14, C12N15